rwj-333369 and Seizures

A novel class of 19 carbamates was synthesized, and their anticonvulsant activity was comparatively evaluated in the rat maximal electroshock (MES) and subcutaneous metrazol (scMet) seizure tests and pilocarpine-induced status epilepticus (SE) model. In spite of the alkyl-carbamates' close structural features, only compounds 34, 38, and 40 were active at the MES test. The analogues 2-ethyl-3-methyl-butyl-carbamate (34) and 2-ethyl-3-methyl-pentyl-carbamate (38) also exhibited potent activity in the pilocarpine-SE model 30 min postseizure onset. Extending the aliphatic side chains of homologous carbamates from 7 to 8 (34 to 35) and from 8 to 9 carbons in the homologues 38 and 43 decreased the activity in the pilocarpine-SE model from ED(50) = 81 mg/kg (34) to 94 mg/kg (35) and from 96 mg/kg (38) to 114 mg/kg (43), respectively. The most potent carbamate, phenyl-ethyl-carbamate (47) (MES ED(50) = 16 mg/kg) contains an aromatic moiety in its structure. Compounds 34, 38, 40, and 47 offer the optimal efficacy-safety profile and, consequently, are promising candidates for development as new antiepileptics.

Topics: Animals; Anticonvulsants; Carbamates; Male; Mice; Neurotoxicity Syndromes; Rats; Rats, Sprague-Dawley; Seizures; Status Epilepticus; Structure-Activity Relationship

This study was initiated to investigate effects of the novel neuromodulator carisbamate (RWJ 333369) in the hippocampal neuronal culture model of status epilepticus and spontaneous epileptiform discharges. Whole-cell current clamp techniques were used to determine the effects of carisbamate on spontaneous recurrent epileptiform discharges (SREDs, in vitro epilepsy), depolarization-induced sustained repetitive firing (SRF) and low Mg(2+)-induced continuous high frequency spiking (in vitro status epilepticus). This in vitro model is an important tool to study the effects of anticonvulsant drugs (AEDs) on SREDs that occur for the life of the neurons in culture. Carisbamate dose dependently blocked the expression and reoccurrence of SREDs. The ED(50) value for its antiepileptic effect was 58.75+/-2.43 microM. Inhibition of SRF is considered a common attribute of many AEDs. Carisbamate (100 microM) significantly decreased SRF in hippocampal neurons. All these effects of carisbamate were reversed during a 5 to 30 min drug washout period. When exposed to low Mg(2+) medium cultured hippocampal neurons exhibit high frequency spiking. This form of in vitro status epilepticus is not effectively blocked by conventional AEDs that are known to be effective in treating status epilepticus in humans. Carisbamate, like phenytoin and phenobarbital, had little or no effect on low Mg(2+)-induced continuous high frequency spiking. These results characterize the effects of carisbamate in the hippocampal neuronal culture model of epileptiform discharges and suggest that the ability of carisbamate to inhibit depolarization-induced SRF may account in part for some of it's anticonvulsant effect.

Topics: Animals; Anticonvulsants; Carbamates; Cells, Cultured; Data Interpretation, Statistical; Dose-Response Relationship, Drug; Electrophysiology; Ethosuximide; Hippocampus; Magnesium Deficiency; Neurons; Patch-Clamp Techniques; Phenytoin; Rats; Rats, Sprague-Dawley; Seizures; Status Epilepticus

Animal models with spontaneous epileptic seizures may be useful in the discovery of new antiepileptic drugs (AEDs). The purpose of the present study was to evaluate the efficacy of carisbamate on spontaneous motor seizures in rats with kainate-induced epilepsy.. Repeated, low-dose (5 mg/kg), intraperitoneal injections of kainate were administered every hour until each male Sprague-Dawley rat had experienced convulsive status epilepticus for at least 3 h. Five 1-month trials (n = 8-10 rats) assessed the effects of 0.3, 1, 3, 10, and 30 mg/kg carisbamate on spontaneous seizures. Each trial involved six AED-versus-vehicle tests comprised of carisbamate or 10% solutol-HS-15 treatments administered as intraperitoneal injections on alternate days with a recovery day between each treatment day.. Carisbamate significantly reduced motor seizure frequency at doses of 10 and 30 mg/kg, and caused complete seizure cessation during the 6-h postdrug epoch in seven of the eight animals at 30 mg/kg. The effects of carisbamate (0.3-30 mg/kg) on spontaneous motor seizures appeared dose dependent.. These data support the hypothesis that a repeated-measures, crossover protocol in animal models with spontaneous seizures is an effective method for testing AEDs. Carisbamate reduced the frequency of spontaneous motor seizures in a dose-dependent manner, and was more effective than topiramate at reducing seizures in rats with kainate-induced epilepsy.

Topics: Analysis of Variance; Animals; Anticonvulsants; Carbamates; Cross-Over Studies; Disease Models, Animal; Dose-Response Relationship, Drug; Drug Administration Schedule; Epilepsy; Fructose; Kainic Acid; Male; Rats; Rats, Sprague-Dawley; Seizures; Time Factors; Topiramate; Video Recording